CN102185818A - Method for capturing and tracking spectrum spreading codes in broadcast positioning system - Google Patents
Method for capturing and tracking spectrum spreading codes in broadcast positioning system Download PDFInfo
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Abstract
The invention provides a method for capturing and tracking spectrum spreading codes in a broadcast positioning system, comprising the following steps: 10, carrying out coarse capturing by a signal segment at the spectrum spreading code position of a transmitted message so as to obtain a captured spectrum spreading code ID and the coarse code phase of a path signal over a threshold, and selecting the path to be precisely captured and tracked; 20, carrying out fine frequency deviation calculation on the path of a precise capture list by a signal segment at the spectrum spreading code position of the untransmitted message; 30, tracking and decoding the path in the track list by the signal section at the spectrum spreading code position of the transmitted message, and calculating time delay difference and a signal-to-noise ratio; and 40, according to the code phases of all paths and the frame structure of the signal, adjusting the positions of input data to be processed in each frame in the previous three steps, and transmitting parameters to a positioning module. The method has the advantages that the computation quantity is small, and the tracked path can be shifted quickly and the used parameter can be positioned according to the change of channels, thereby improving the positioning accuracy.
Description
[technical field]
The present invention relates to a kind of broadcasting framing signal, particularly broadcast catching and tracking of spreading code in the framing signal.
[background technology]
Open day is 2011.02.16 day, publication number is the Chinese patent " broadcasting framing signal generation method; localization method and device " of CN101977172A, generate broadcasting framing signal by the mode that increases spreading code original in based on the broadcast system of OFDM (OFDM) technology, the spreading code transmitting text in a bit of time of a frame that increases, and former broadcast singal removed, transmitting text not in the most of the time section, keep former broadcast singal, and the energy of spread-spectrum signal is reduced to the degree that does not influence former broadcast singal substantially, receiver is by receiving this signal, broadcast program can either be received, positioning function can be realized again.Yet spreading code is arranged not only in the broadcasting framing signal, also has original OFDM (OFDM) signal, ofdm signal is very big to the interference of spreading code in the most of the time section, for example, the high 20db of intensity of the signal that the strength ratio emitter B of the signal that the emitter A that receives at the three unities sends sends, and in the broadcasting framing signal at the spreading code place of transmitting text not, ofdm signal is than the high 20db of spread-spectrum code signals intensity, then receiving terminal is when the spreading code that emitter B is sent is caught and followed the tracks of, and is subjected to the strong 40db of interference ratio spreading code of the ofdm signal that emitter A sends at the spreading code place of transmitting text not.
Can be to the catching of spreading code, tracking and localization method in the broadcasting framing signal with reference to the method for catching, following the tracks of and locating of GPS (global positioning system), but because the condition of city broadcast channel is much more abominable than satellite channel, most of local no direct signal, the method precision of the geometry location of usefulness GPS is lower.Open day is 2009.12.30 day, publication number is the Chinese patent " localization method in a kind of mobile communication system and portable terminal, location-server " of CN101616482A, disclose a kind of technology and positioned, to improve the method for positioning accuracy based on parameter matching.Adopt catching and tracking of GPS, catch the spreading code that to receive earlier, again the spreading code that captures is followed the tracks of, if tracking losing lock, just carry out reacquisition, because the sensitivity of following the tracks of will be better than the sensitivity of catching greatly, therefore in identical place, the delay inequality parameter that receiver obtains may be different.For example, can follow the tracks of two paths x that certain emitter sends and the signal of y at place A, but the signal that can only catch path x; Can follow the tracks of two paths x that this emitter sends and the signal of y at place B, but the signal that can only catch path y.If then receiver is always at place A, just can only catch signal with track path x, if receiver moves to place A from place B, the middle situation that can not follow the tracks of losing lock just can only be caught the signal with track path y, like this, same path difference of following the tracks of at place A, the time delay value that obtains is just different, and is just different with the delay inequality of other emitter, directly influenced the precision based on the localization method of parameter matching.
[summary of the invention]
The technical problem to be solved in the present invention is to provide a kind of catching and tracking of spreading code in the navigation system of broadcasting, and its operand is little, can switch the path of tracking and the parameter that use the location fast according to the variation of channel, improves the accuracy of location.
The present invention is achieved in that a kind of catching and tracking of spreading code in the navigation system of broadcasting, the time span that specifically comprises the steps: the spreading code position of transmitting text in step 10, the usefulness frame data that receive is that the segment signal of T is slightly caught the spreading code of catching the spreading code ID correspondence in the tabulation, obtains spreading code ID that can capture and the thick code phase that surpasses the path signal of threshold value thereof; The code phase that the thick code phase of the path signal of each spreading code correspondence of slightly capturing and this spreading code is being carried out the path signal that essence catches and follow the tracks of compares, obtain the new route signal of this spreading code, the new route signal is judged, determine whether that it be added essence catches and follow the tracks of tabulation, if not capturing any paths signal and essence catches tabulation and follows the tracks of tabulation for empty, then withdraw from and catch and follow the tracks of, carry out frame synchronization again; Step 20, with in the frame data that receive not the plural segment signal of the spreading code position of transmitting text essence is caught each path in the tabulation carry out fine frequency offset and calculate, the signal of certain paths essence catch calculate finish after, this path caught the tabulation from essence remove, and judge whether successful essence catches, if success, then change the state of this path in following the tracks of tabulation into smart acquisition success, and the accurate frequency bias of calculating is updated to follows the tracks of tabulation, if unsuccessful, then this path is removed from follow the tracks of tabulation; Step 30, be that the segment signal of T carries out the tracking of carrier phase and code phase to each path of following the tracks of smart acquisition success in the tabulation with the time span of the spreading code position of transmitting text in the frame data in the step 10, and solve the text of each emitter emission in the broadcasting framing signal, calculate the delay inequality and the signal to noise ratio of each paths signal of each emitter, and these parameters are passed to locating module position; Step 40, according to the code phase of following the tracks of all paths in the tabulation and the frame structure of signal, step 10 is jumped in the position of next frame input data to be processed in the set-up procedure 10,20,30, and the next frame data are handled.
Further, the time span of the spreading code position of transmitting text is the segment signal of T in the frame data described in the step 10,30, this segment signal length T is less than the length of the signal of the spreading code position of transmitting text, and is the integral multiple of spreading code Cycle Length; Then, need before slightly catching, carry out down-conversion with rough frequency deviation earlier, to improve the performance of slightly catching to this segment signal when rough frequency deviation during greater than 1/T.
Further, in the step 10, without any supplementary the time, catch tabulation and comprised all spreading code ID; When supplementary is arranged, catch tabulation only comprise the spreading code ID that might receive; In the step 10, the thick code phase that obtains surpassing the path signal of threshold value specifically comprises: a segment signal that will the spreading code position of transmitting text in the described frame data and the prior spreading code of storing carry out cyclic shift one by one in this segment signal length relevant, and mould value and the associated gate limit value of the relevant correlation that obtains that will be shifted compare, and counting above the displacement of the spreading code of the prior storage of associated gate limit value correspondence is the thick code phase in path; Exist if surpass the mould value of associated gate limit value, think that then the broadcasting framing signal of emitter of this spreading code ID correspondence can not capture.
Further, in the step 10, the new route signal that obtains this spreading code specifically comprises: the difference of code phase that the thick code phase of the path signal that this spreading code slightly captures and this spreading code are carrying out all path signals that essence catches and follow the tracks of is during all greater than a code phase thresholding, think that this path signal is new path signal, this code phase thresholding is the minimum value of the discernmible two paths signal code phase differences of tracking module.
Further, in the step 10, described the new route signal is judged, determine whether it to be added essence catch and follow the tracks of the tabulation be meant, described new route signal adds essence with it and catches and follow the tracks of tabulation when satisfying the condition of the strongest path signal that path signal bar number system of not transfiniting that essence catches and follow the tracks of or the new route signal that captures are this emitters or article one path signal; The path signal bar number of catching or following the tracks of in essence surpasses restriction, and when the new route signal that captures is the strongest path signal of this emitter or article one path signal, it to be added essence and catch and follow the tracks of tabulation, need remove essence and catch and follow the tracks of a paths signal in the tabulation, it is as follows to remove rule: the essence that preferentially removes this emitter correspondence is caught uncompleted path, take second place to remove and follow the tracks of unstabilized path, remove the minimum path of signal to noise ratio at last.
Further, in the step 20, when described fine frequency offset calculates, the signal of the spreading code position of transmitting text does not carry out down-conversion with rough frequency deviation earlier, catch the spreading code ID that the essence in the tabulation catches and the code phase of this path signal according to essence then, utilize the spread spectrum code sequence of storage in advance that it is carried out despreading, carry out the method for FFT with despreading result and calculate accurate frequency bias the equally spaced data of plural number section, improving its performance, whether surpass thresholding according to the peak value of the mould value of FFT and judge that essence catches whether success.
Further, to choosing of the described plural number equally spaced data of section, the time span of the spreading code position of the transmitting text of the frequency range of Ji Suaning from step 10 is that the original position of the segment signal of T is divided into the plural number section as frame starting point with the data of a frame length as required, the frequency range that the hop count that divides can calculate more at most is big more, but performance is poor more; Then each segment data front length being added maximum multipath delay spread and back length greater than T is that the data of maximum multipath delay spread are removed, so just obtained to carry out the data segment of despreading, it is enough big that the length of each data segment is wanted, with the data that guarantee each data segment stronger spreading gain is arranged, the last frequency accuracy that calculates as required, determine the quantity of calculative data segment, quantity is many more, and the frequency accuracy that calculates is high more.
Further, in the step 30, when carrier phase and code phase are followed the tracks of, the method of using GPS receiver carrier phase and code phase to follow the tracks of, the time span of just using the spreading code position of transmitting text in the frame data that receive are the despreading result that the despreading result of the segment signal of T replaces frame data.
Further, in the step 30, the parameter that is transferred to locating module comprises: all are following the tracks of the spreading code ID and the positional information thereof of the path signal of the emitter of catching with essence, all of these emitters are being followed the tracks of and the smart path signal of catching and the delay inequality of first path signal that receives, the tracking stable state in above-mentioned each path provides signal to noise ratio for following the tracks of stable path; When described locating module is used localization method based on parameter matching, preferentially choose the delay inequality of the path signal of signal to noise ratio maximum in the stable path signal of the tracking of these emitters and signal to noise ratio match parameter as this emitter; When described locating module during with the geometry location method, the delay inequality that locating module is chosen article one path signal of these emitters positions calculating in conjunction with the positional information of these emitters.
Further, in the step 40, according to the code phase of following the tracks of all paths in the tabulation and the frame structure of signal, set-up procedure 10,20, the position of next frame input data to be processed in 30, promptly skip the data of 1 frame, the method of choosing that segment data in step 10 and 30 is as follows: the starting point of spreading code position of establishing the transmitting text of last path signal that receives in all path signals of all emitters of catching and following the tracks of is A, the end point of the spreading code position of the transmitting text of first path signal that receives in all path signals of all emitters of having caught and having followed the tracks of is B, mid point with A and B is the center, the sequence of choosing length and be T is this segment signal, and the choosing method of step 20 next frame input data to be processed is that the original position of the segment signal of T is chosen by the described method of claim 7 according to the time span of the spreading code position of transmitting text in the frame data in step 10 and 30.
The present invention has following advantage:
The present invention only slightly catches and follows the tracks of reducing complexity with the signal at the spreading code place of transmitting text, catches and only carry out essence with the signal at the spreading code place of transmitting text not, has improved smart accuracy of catching;
The present invention because more parameter is provided, has improved locating accuracy for the localization method based on match parameter.Can increase the delay inequality information of mulitpath and signal to noise ratio (or poor signal to noise) information parameter as match parameter based on the localization method of match parameter, catch and can be also the path signal of the emitter followed the tracks of be carried out, path signal with timely discovery increase, and follow the tracks of the mulitpath signal simultaneously, calculate signal to noise ratio, and provide each paths signal whether stable information, make things convenient for the choosing of match parameter of localization method;
The delay inequality that the fully compatible localization method based on how much of the present invention, locating module are chosen article one path signal of these emitters is carried out computing and can be obtained higher precision, the method that locating module also can adopt geometry location and Matching Location to combine.If only adopt localization method based on how much, this method can be optimized for and only follow the tracks of a paths signal, slightly catch and only see whether there be the path signal more Zao than the path signal of following the tracks of, if have just to change into and follow the tracks of this path signal, in addition, because only a bit of data are slightly caught and followed the tracks of, operand reduces greatly, can use the method that cross-correlation is eliminated among the GPS to improve systematic function.
[description of drawings]
The present invention is further illustrated in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is the inventive method schematic flow sheet.
Fig. 2 is the frame structure schematic diagram of CMMB.
Fig. 3 is the structural representation in the gold sign indicating number time slot of stack.
[embodiment]
As Fig. 1, be that specific embodiment describes with a kind of broadcasting framing signal below based on CMMB (China Mobile multimedia broadcasting).
Be illustrated in figure 2 as the frame structure of CMMB, per 1 second is 1 frame, is divided into 40 time slots, and the length of each time slot is 25ms, comprises 1 beacon and 53 OFDM symbols, and bit rate is 10M.The broadcasting framing signal is 511 a Gold sign indicating number of stack on the CMMB signal, and the bit rate of Gold sign indicating number is 5M, and the Gold sign indicating number of stack be the cycle repetition with time slot (25ms).
As shown in Figure 3, the structure chart of Gold sign indicating number in time slot of stack.Wherein, harbour part (136us) is removed original C MMB signal, has only the Gold sign indicating number, and the CMMB signal energy of signal energy and back is suitable; Superimposed code partly keeps original CMMB signal, and the signal energy of the Gold sign indicating number of stack is lower than harbour 20db.The Gold sign indicating number of harbour part is modulated text with BPSK, and the duration of every bit text is 50ms; The superimposed code part is not modulated text.The Gold sign indicating number always has 20 groups, its ID numbering from 0 to 19.
The present invention is a kind of to broadcast catching and tracking of spreading code in the navigation system, supposes frame synchronization success, has found the Position Approximate of harbour, and has calculated rough frequency deviation.
The present invention is a kind of to broadcast catching and tracking of spreading code in the navigation system, specifically comprises the steps:
Step 10, be that the segment signal of 102.2us is slightly caught the spreading code of catching the spreading code ID correspondence in the tabulation, obtain spreading code ID that can capture and the thick code phase that surpasses the path signal of threshold value thereof with the time span of harbour position in the time slot data that receive; The code phase that the thick code phase of each path signal of each spreading code of slightly capturing and this spreading code is being carried out each path signal that essence catches and follow the tracks of compares, obtain the new route signal of this spreading code, the new route signal is judged, determined whether that it be added essence catches and follow the tracks of tabulation; Jump to step 20; Do not catch tabulation and follow the tracks of tabulation if capture any paths signal and essence, then withdraw from and catch and follow the tracks of, carry out frame synchronization again for empty.
When rough frequency deviation during, need before slightly catching, carry out down-conversion with rough frequency deviation earlier, to improve the performance of slightly catching to this segment signal greater than the 10KHz left and right sides.But in order to improve positioning performance, receiver generally adopts TCXO (temperature compensating crystal oscillator) as the clock source, the stability of TCXO is generally less than 2ppm (2/1000000ths), and the tranmitting frequency of present CMMB signal is less than 1GHz, maximum of the frequency deviation that is caused by crystal oscillator can be 2KHz like this, and the frequency deviation that Doppler effect causes generally can not surpass 500Hz, therefore can not carry out the judgement of rough frequency deviation when receiver adopts TCXO as the clock source.
Without any supplementary the time, catch tabulation and comprised all spreading code ID (0 to 19); When supplementary is arranged, catch tabulation only comprise the spreading code ID that might receive; Described supplementary can be passed through text or other Channel Transmission; Also can store the positional information of each emitter in advance, determine to receive the signal of which emitter then according to the position of orienting.
The thick code phase that obtains surpassing the path signal of threshold value specifically comprises: it is relevant that time span that will harbour position in the described time slot data is that a segment signal and the prior spreading code of storing of 102.2us carries out cyclic shift one by one in this segment signal length, and mould value and the threshold value of the relevant correlation that obtains that will be shifted compare, and counting above the displacement of the spreading code of the prior storage of threshold value correspondence is the thick code phase in path; Exist if surpass the mould value of threshold value, think that then the broadcasting framing signal of emitter of this spreading code ID correspondence can not capture.Described threshold value can determine according to the certain multiple all on duty of the mould value of all correlations, also can determine according to the certain multiple maximum on duty of the mould value of the outer correlation of the possible multipath expansion time in mould value maximum position.Cyclic shift is relevant can to reduce operand with the method for FFT (fast Fourier transform), and concrete steps are as follows: step 1.1, the input data of harbour place 102.2 microseconds to be processed are carried out the FFT conversion and get conjugation obtaining sequence A.Jump to step 1.2; If step 1.2 is caught the spreading code ID that does not catch in addition in the tabulation, with this locality in advance the sequence that obtains by identical sample rate of this spreading code of storage the result that is FFT take out to multiply each other by element and obtain sequence B with sequence A, jump to step 1.3; Otherwise finish; Step 1.3, sequence B is carried out IFFT obtain sequence C, jump to step 1.4; The average of first prime modulus value takes advantage of certain multiple to obtain threshold value among step 1.4, the sequence of calculation C, jumps to step 1.5; Step 1.5, mould value and threshold value with each element in sequence C compare, as long as there is the element that surpasses threshold value, just think that the broadcasting framing signal of emitter of this spreading code ID correspondence can capture, by the element that the surpasses threshold value thick code phase that this path is determined in corresponding position in sequence, jump to step 1.2.
The difference of code phase that the thick code phase of the path signal that this spreading code slightly captures and this spreading code are carrying out all path signals that essence catches and follow the tracks of is during all greater than a code phase thresholding, think that this path signal is new path signal, this code phase thresholding is the minimum value of the discernmible two paths signal code phase differences of tracking module.
Described the new route signal is judged, determine whether it to be added essence catch and follow the tracks of the tabulation be meant, described new route signal adds essence with it and catches and follow the tracks of tabulation when satisfying the condition of the strongest path signal that path signal bar number system of not transfiniting that essence catches and follow the tracks of or the new route signal that captures are this emitters or article one path signal; The path signal bar number of catching or following the tracks of in essence surpasses restriction, and when the new route signal that captures is the strongest path signal of this emitter or article one path signal, it to be added essence and catch and follow the tracks of tabulation, need remove essence and catch and follow the tracks of a paths signal in the tabulation.It is as follows to remove rule: the essence that preferentially removes this emitter correspondence is caught uncompleted path, takes second place to remove and follows the tracks of unstabilized path, removes the minimum path of signal to noise ratio at last.Present embodiment can be simultaneously carries out essence to the path signal of 8 emitters to be caught and follows the tracks of, and each emitter can be followed the tracks of 6 paths signals simultaneously, and essence is caught 3 paths signals.Therefore smart catching do not finished, follows the tracks of stable and the minimum path of signal to noise ratio all has many; If satisfying the essence of the condition that removes catches and does not finish or follow the tracks of unstabilized path and have many, then remove the path that this catches these path correspondence position correlation mould value minimums, if some path correlation mould value is also identical, then remove the last path that arrives in these paths; There are many if satisfy the minimum path of signal to noise ratio of the condition that removes, then remove the last path that arrives in these paths.
Fine frequency offset calculating is carried out in each path that 25 segment signals of superimposed code position are caught in the tabulation essence in step 20, the usefulness time slot data that receive; The signal of certain paths essence catch calculate finish after, this path caught the tabulation from essence remove, and judge that essence catches whether success, if success, then change the state of this path in following the tracks of tabulation into smart acquisition success, and the accurate frequency bias of calculating is updated to the tracking tabulation; If unsuccessful, then this path is removed from follow the tracks of tabulation; Jump to step 30;
Fine frequency offset calculates earlier not, and the signal of the spreading code position of transmitting text carries out down-conversion with rough frequency deviation, the code phase of catching spreading code ID in the tabulation and this path according to essence carries out despreading with the spread spectrum code sequence of local storage to it then, calculate accurate frequency bias with the method that the 1024 intersegmental despreading results that are divided into 1 millisecond data are carried out FFT, to improve its performance.Whether surpass thresholding according to the peak value of the mould value of FFT and judge that essence catches whether success.The FFT thresholding can determine according to the certain multiple all on duty of FFT result's mould value, also can determine according near the certain multiple maximum on duty of the mould value of the extra-regional correlation peak value of FFT result's mould value.
Intersegmental to be divided into 1 millisecond the choosing method of data as follows to 1024: the original position of the data that the 25ms of a time slot will be calculated from step 1 and step 3 begins, be divided into 25 parts, the data of every part of 1ms are removed the data of foremost 153.3 microseconds and the data of 51.1 microseconds backmost, have so just obtained the smart one piece of data that carries out despreading of catching.The frequency accuracy that essence is caught can arrive about 1Hz, and the frequency computation part scope can be from-500Hz to 500Hz.
Step 30, the tracking of carrier phase and code phase is carried out in each path of following the tracks of smart acquisition success in the tabulation with that segment data in the step 10, and solve the text of each emitter emission in the broadcasting framing signal, calculate the delay inequality and the signal to noise ratio of each paths signal of each emitter, and these parameters are passed to locating module position;
The method of the tracking of described carrier phase and code phase can be with reference to the method for GPS tracking, use FLL (frequency-locked loop) is in conjunction with PLL (phase-locked loop) or only lock carrier phase with PLL, use DLL (delay-locked loop) lock code phase place, also can use the method for Kalman filtering to improve its performance.Choosing of FLL, PLL and DLL discriminator can be with reference to the tracking of GPS.The signal of following the tracks of according to each path signal after the despreading on I (homophase) road that obtains and Q (quadrature) road carries out signal-to-noise ratio (SNR) estimation; The I road value of each track path signal of same emitter is added up, adjudicate the text of this emitter transmission then; Calculate the delay inequality of each path signal according to the code phase of each path signal locking, the judgement of loop-locking and losing lock can be with reference to the determination methods of locking of GPS tracking intermediate ring road and losing lock.If use FLL at first to carry out bit synchronization, determine the edge of text saltus step, concrete grammar also can be with reference to the tracking of GPS.The difference that this method and GPS follow the tracks of is not continuous in the data of handling mainly, the result that need replace the despreading of time slot 25ms data with the result of the data despreading of the 102.2us of harbour, because there is not the strong jamming of ofdm signal in the spreading code position of transmitting text, and its length is much larger than the length of the spreading code position of transmitting text, if therefore use this partial data in the tracing process, to the raising of performance seldom, and the operand that increases is very big.
The parameter that is transferred to locating module comprises: all are following the tracks of the spreading code ID and the positional information thereof of the path signal of the emitter of catching with essence, all of these emitters are being followed the tracks of and the smart path signal of catching and the delay inequality of first path signal that receives, the tracking stable state in above-mentioned each path provides signal to noise ratio for following the tracks of stable path; When described locating module is used localization method based on parameter matching, preferentially choose the delay inequality of the path signal of signal to noise ratio maximum in the stable path signal of the tracking of these emitters and signal to noise ratio match parameter as this emitter; When described locating module during with the geometry location method, the delay inequality that locating module is chosen article one path signal of these emitters positions calculating in conjunction with the positional information of these emitters.The method that locating module also can adopt geometry location and Matching Location to combine.If only adopt the localization method based on how much, this method can be optimized for only follows the tracks of a paths signal, slightly catches and only sees whether there be the path signal more Zao than the path signal of following the tracks of, and follows the tracks of this path signal if having just to change into.
Step 40, according to the code phase of following the tracks of all paths in the tabulation and the frame structure of signal, the position of next frame input data to be processed in the set-up procedure 10,20,30; Jump to step 10, the next frame data are handled;
The probability that the spreading code position signal of certain base station transmits text is disturbed for the ofdm signal that reduces other base station as far as possible, skip the data of 1 frame, the method of choosing that segment data in step 10 and 30 is as follows: the starting point of spreading code position of establishing the transmitting text of last path signal that receives in all path signals of all emitters of catching and following the tracks of is A, the end point of the spreading code position of the transmitting text of first path signal that receives in all path signals of all emitters of having caught and having followed the tracks of is B, mid point with A and B is the center, and the sequence of choosing length and be 102.2us is this segment signal.The choosing method of step 20 next frame input data to be processed method described in 20 is set by step chosen according to the original position of that segment data in step 10 and 30.When choosing for the first time that segment data in step 10 and 30, think the path of having only one to catch and followed the tracks of, its starting point and end point are obtained by frame synchronization.
This method that the present invention proposes is owing to only slightly catch and follow the tracks of a bit of data, and operand reduces greatly, can use the method that cross-correlation is eliminated among the GPS to improve systematic function.Method among the present invention does not limit its implementation, can use software realization, way of hardware and software combination to realize or the realization of pure hardware.
The above, only for preferred embodiment of the present invention, so can not limit scope of the invention process according to this, i.e. the equivalence of doing according to claim of the present invention and description changes and modification, all should still belong in the scope that the present invention contains.
Claims (10)
1. broadcast catching and tracking of spreading code in the navigation system for one kind, it is characterized in that: specifically comprise the steps:
Step 10, be that the segment signal of T is slightly caught the spreading code of catching the spreading code ID correspondence in the tabulation, obtain spreading code ID that can capture and the thick code phase that surpasses the path signal of threshold value thereof with the time span of the spreading code position of transmitting text in the frame data that receive; The code phase that the thick code phase of the path signal of each spreading code correspondence of slightly capturing and this spreading code is being carried out the path signal that essence catches and follow the tracks of compares, obtain the new route signal of this spreading code, the new route signal is judged, determine whether that it be added essence catches and follow the tracks of tabulation, if not capturing any paths signal and essence catches tabulation and follows the tracks of tabulation for empty, then withdraw from and catch and follow the tracks of, carry out frame synchronization again;
Step 20, with in the frame data that receive not the plural segment signal of the spreading code position of transmitting text essence is caught each path in the tabulation carry out fine frequency offset and calculate, the signal of certain paths essence catch calculate finish after, this path caught the tabulation from essence remove, and judge whether successful essence catches, if success, then change the state of this path in following the tracks of tabulation into smart acquisition success, and the accurate frequency bias of calculating is updated to follows the tracks of tabulation, if unsuccessful, then this path is removed from follow the tracks of tabulation;
Step 30, be that the segment signal of T carries out the tracking of carrier phase and code phase to each path of following the tracks of smart acquisition success in the tabulation with the time span of the spreading code position of transmitting text in the frame data in the step 10, and solve the text of each emitter emission in the broadcasting framing signal, calculate the delay inequality and the signal to noise ratio of each paths signal of each emitter, and these parameters are passed to locating module position;
Step 40, according to the code phase of following the tracks of all paths in the tabulation and the frame structure of signal, step 10 is jumped in the position of next frame input data to be processed in the set-up procedure 10,20,30, and the next frame data are handled.
2. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: the time span of the spreading code position of transmitting text is the segment signal of T in the frame data described in the step 10,30, this segment signal length T is less than the length of the signal of the spreading code position of transmitting text, and is the integral multiple of spreading code Cycle Length; Then, need before slightly catching, carry out down-conversion with rough frequency deviation earlier, to improve the performance of slightly catching to this segment signal when rough frequency deviation during greater than 1/T.
3. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1 is characterized in that: in the step 10, without any supplementary the time, catching tabulation and having comprised all spreading code ID; When supplementary is arranged, catch tabulation only comprise the spreading code ID that might receive; In the step 10, the thick code phase that obtains surpassing the path signal of threshold value specifically comprises: a segment signal that will the spreading code position of transmitting text in the described frame data and the prior spreading code of storing carry out cyclic shift one by one in this segment signal length relevant, and mould value and the associated gate limit value of the relevant correlation that obtains that will be shifted compare, and counting above the displacement of the spreading code of the prior storage of associated gate limit value correspondence is the thick code phase in path; Exist if surpass the mould value of associated gate limit value, think that then the broadcasting framing signal of emitter of this spreading code ID correspondence can not capture.
4. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 10, the new route signal that obtains this spreading code specifically comprises: the difference of code phase that the thick code phase of the path signal that this spreading code slightly captures and this spreading code are carrying out all path signals that essence catches and follow the tracks of is during all greater than a code phase thresholding, think that this path signal is new path signal, this code phase thresholding is the minimum value of the discernmible two paths signal code phase differences of tracking module.
5. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 10, described the new route signal is judged, determine whether it to be added essence catch and follow the tracks of the tabulation be meant, described new route signal adds essence with it and catches and follow the tracks of tabulation when satisfying the condition of the strongest path signal that path signal bar number system of not transfiniting that essence catches and follow the tracks of or the new route signal that captures are this emitters or article one path signal; The path signal bar number of catching or following the tracks of in essence surpasses restriction, and when the new route signal that captures is the strongest path signal of this emitter or article one path signal, it to be added essence and catch and follow the tracks of tabulation, need remove essence and catch and follow the tracks of a paths signal in the tabulation, it is as follows to remove rule: the essence that preferentially removes this emitter correspondence is caught uncompleted path, take second place to remove and follow the tracks of unstabilized path, remove the minimum path of signal to noise ratio at last.
6. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 20, when described fine frequency offset calculates, the signal of the spreading code position of transmitting text does not carry out down-conversion with rough frequency deviation earlier, catch the spreading code ID that the essence in the tabulation catches and the code phase of this path signal according to essence then, utilize the spread spectrum code sequence of storage in advance that it is carried out despreading, carry out the method for FFT with despreading result and calculate accurate frequency bias the equally spaced data of plural number section, improving its performance, whether surpass thresholding according to the peak value of the mould value of FFT and judge that essence catches whether success.
7. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 6, it is characterized in that: to choosing of the described plural number equally spaced data of section, the time span of the spreading code position of the transmitting text of the frequency range of Ji Suaning from step 10 is that the original position of the segment signal of T is divided into the plural number section as frame starting point with the data of a frame length as required, the frequency range that the hop count that divides can calculate more at most is big more, but performance is poor more; Then each segment data front length being added maximum multipath delay spread and back length greater than T is that the data of maximum multipath delay spread are removed, so just obtained to carry out the data segment of despreading, it is enough big that the length of each data segment is wanted, with the data that guarantee each data segment stronger spreading gain is arranged, the last frequency accuracy that calculates as required, determine the quantity of calculative data segment, quantity is many more, and the frequency accuracy that calculates is high more.
8. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 30, when carrier phase and code phase are followed the tracks of, the method of using GPS receiver carrier phase and code phase to follow the tracks of, the time span of just using the spreading code position of transmitting text in the frame data that receive are the despreading result that the despreading result of the segment signal of T replaces frame data.
9. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 30, the parameter that is transferred to locating module comprises: all are following the tracks of the spreading code ID and the positional information thereof of the path signal of the emitter of catching with essence, all of these emitters are being followed the tracks of and the smart path signal of catching and the delay inequality of first path signal that receives, the tracking stable state in above-mentioned each path provides signal to noise ratio for following the tracks of stable path; When described locating module is used localization method based on parameter matching, preferentially choose the delay inequality of the path signal of signal to noise ratio maximum in the stable path signal of the tracking of these emitters and signal to noise ratio match parameter as this emitter; When described locating module during with the geometry location method, the delay inequality that locating module is chosen article one path signal of these emitters positions calculating in conjunction with the positional information of these emitters.
10. a kind of catching and tracking of spreading code in the navigation system of broadcasting according to claim 1, it is characterized in that: in the step 40, according to the code phase of following the tracks of all paths in the tabulation and the frame structure of signal, set-up procedure 10,20, the position of next frame input data to be processed in 30, promptly skip the data of 1 frame, the method of choosing that segment data in step 10 and 30 is as follows: the starting point of spreading code position of establishing the transmitting text of last path signal that receives in all path signals of all emitters of catching and following the tracks of is A, the end point of the spreading code position of the transmitting text of first path signal that receives in all path signals of all emitters of having caught and having followed the tracks of is B, mid point with A and B is the center, the sequence of choosing length and be T is this segment signal, and the choosing method of step 20 next frame input data to be processed is that the original position of the segment signal of T is chosen by the described method of claim 7 according to the time span of the spreading code position of transmitting text in the frame data in step 10 and 30.
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